Re: [cf-satellite] [CF-metadata] Sharing quality flags amongmultiple variables

• To: "Thomas Lavergne" <t.lavergne@xxxxxx>
• Subject: Re: [cf-satellite] [CF-metadata] Sharing quality flags amongmultiple variables
• From: "Mike Grant" <mggr@xxxxxxxxx>
• Date: Wed, 02 Nov 2011 14:24:23 +0000

Hi Thomas,

On 02/11/11 09:37, Thomas Lavergne wrote:
> My issue is then to associate a 'status_flag' variable with both
> sea_ice_x_displacement and sea_ice_y_displacement.
> 
> Currently, my "status_flag" variable (which uses flag_values and
> flag_meanings attributes) has standard name "sea_ice_x_displacement
> status_flag" but what I really would like is something like
> "sea_ice_x_displacement,sea_ice_y_displacement status_flag" (or any
> other extension the CF list agrees on) to inform a machine (or a
> human) that my status_flag applies to both components of my ice drift
> vector.

I think the currently recommended standard approach is that you have
something like:

 float sea_ice_x_displacement(...) ;
    sea_ice_x_displacement:ancillary_variables = "sea_ice_flags" ;
    ....
 float sea_ice_y_displacement(...) ;
    sea_ice_y_displacement:ancillary_variables = "sea_ice_flags" ;
    ....
 int sea_ice_flags(...) ;
    sea_ice_flags:flag_values = "0, 1, 2, ..."
 ;
    sea_ice_flags:flag_meanings = "meaning0 meaning1 meaning2...";
    ....

The association between variables and the flags variable is purely by
the ancillary_variables attribute.  There is no requirement for the
names of the variables to be similar - i.e. your flags variable for the
x displacement doesn't have to be called sea_ice_x_displacement_flags.
You can call the flags anything you like and just associate it using the
ancillary_variables attribute.  Obviously, if you pick something
human-comprehensible, that's better.

Cheers,

Mike.



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• References:
  • Re: [cf-satellite] [CF-metadata] Sharing quality flags amongmultiple variables
    • From: Thomas Lavergne